class Solution:
    def singleNumber(self, nums):
        dic = set()
        for i in nums:
            if i in dic:
                dic.remove(i)
            else:
                dic.add(i)
        return list(dic)


if __name__ == '__main__':
    so = Solution()
    m = [1,2,1,3,2,5]
    r = so.singleNumber(m)
    print(r)
